Certain Dell monitors require a large video bandwidth, such as the U4919DW monitor. When these monitors use a USB Type-C connection, the USB 3.0 devices connected directly to the monitor may experience erratic performance.
When using a USB Type-C connection on these monitors, the bandwidth is shared over that one cable for both the USB video content and for any USB 3.0 data used by any USB 3.0 devices connected directly to the monitor. For example, when using dual monitors operating at the 2560x1440 or higher resolution, the video bandwidth over the USB Type-C connection is not enough to drive both monitors at the best resolution.
Dell Technologies recommends that you do not daisy chain devices through the monitor off of one cable. It is best practice to use two separate connections or cables coming from the computer:
An example would be to use the USB Type-C connection for all the USB 3.0 devices. Then, use a USB Type-C to DisplayPort dongle so that the DisplayPort can supply video to the monitor. Sometimes, video can also be obtained using the HDMI connection on the computer instead.